1. Field of the Invention
The invention relates to dispensing containers in which a dispensing flowpath is provided with a mixing structure for two or more initially-isolated components, such as a resin and a curing agent. More particularly, the invention provides an improved static mixing device for mixing plural flowable components by combining, subdividing and recombining streams of the composition, wherein the composition flows substantially exclusively in one direction along the flowpath from two or more source compartments to a discharge opening.
2. Prior Art
Static mixing devices for dispensing containers are generally known. These devices can include discharge conduits defined in part by fixed structures that partially obstruct a stream of material flowing generally through the device from a source to a discharge, so as to cause mixing. The obstructions guide the materials along a circuitous path with eddies and the like, and mix the multi-component composition more thoroughly than is possible where material streams from plural sources are carried along an unobstructed conduit. The mixing process is accomplished by continuously dividing and recombining the material stream (i.e., the two or more flowing components). In an unobstructed conduit such streams can flow side by side without substantial mixing. This is particularly true for relatively viscous materials.
The flow is driven generally by compressing the materials, e.g., in a flexible bag, to squeeze the material forward in the direction of flow. This can be done manually or with the aid of a roller or other compressing mechanism.
An example of a dispensing container with mixing structures as described is disclosed in U.S. Pat. No. 4,952,068--Flint, the disclosure of which is hereby incorporated. The Flint conduit is formed from opposing sheets of material defining a flexible multi-component squeeze container. Seams join the perimeters of opposing sheets to form a flexible container, with at least one internal wall dividing the container into at least two storage compartments for isolating the flowing components before they are brought together for use. At least one internal wall further downstream toward the outlet is provided for mixing. External pressure on the container bursts at least one isolating wall or seam and forces the plural components to combine. The materials combine in an initial mixing area along the flowpath in the container, downstream of the walls defining the storage compartments. Downstream dividing walls define the path from the initial mixing area to the container outlet. The walls divert the flow and cause the stream of flowing material to separate and recombine one or more times prior to exit from the container, which provides improved mixing as compared to a substantially laminar flow through an unobstructed conduit.
The material is squeezed along the flowpath by applying a peristaltic squeezing action to the flexible container. The obstructions and the squeezing action cause flow variations; however, not all of the resulting variations are beneficial for mixing. Depending on the care taken in squeezing and kneading the material along the flowpath in a forward direction, portions of the components can be forced to flow in a reverse direction, i.e., toward the storage compartments, as they separate and recombine in the sinuous path permitted by the obstructions. This is disadvantageous since these mixed components can move back toward the storage compartments and contaminate or change the relative concentrations of the as yet unmixed components.
U.S. Pat. No. 5,516,209--Flint, which is also incorporated herein, discloses a mixing dispenser in the form of a flexible mixing conduit with durable means attached to a source of plural flowable components, e.g., a multi-component sealant cartridge. The mixing dispenser is adapted for mixing the flowable components as they are dispensed. A support structure is provided that facilitates kneading, as well as compression of the conduit to empty it. The support structure can be used as an applicator blade which is also reusable. Here again, the plural components have a tendency sometimes to flow in a reverse direction, i.e., causing incomplete emptying of the dispenser and/or requiring more compression strokes to obtain the total mixed contents.